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Subpicotesla atomic magnetometry with a microfabricated vapour cell

Abstract

Highly sensitive magnetometers capable of measuring magnetic fields below 1 pT have an impact on areas as diverse as geophysical surveying1, the detection of unexploded ordinance2, space science3, nuclear magnetic resonance4,5, health care6 and perimeter and remote monitoring. Recently, it has been shown that laboratory optical magnetometers7,8, based on the precession of the spins of alkali atoms in the vapour phase, could achieve sensitivities in the femtotesla range, comparable to9,10,11,12, or even exceeding13, those of superconducting quantum interference devices6. We demonstrate here an atomic magnetometer based on a millimetre-scale microfabricated alkali vapour cell with sensitivity below 70 fT Hz−1/2. Additionally, we use a simplified optical configuration that requires only a single low-power laser. This result suggests that millimetre-scale, low-power femtotesla magnetometers are feasible, and we support this proposition with a simple sensitivity scaling analysis. Such an instrument would greatly expand the range of applications in which atomic magnetometers could be used.

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Figure 1: Atomic magnetometry with a micromachined alkali vapour cell.
Figure 2: Magnetometer sensitivity scaling under near-optimal conditions for linewidth.

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Acknowledgements

The authors acknowledge valuable discussions with L. Hollberg, M. Romalis and D. Budker and thank S. Schima and L. Liew for help with the cell fabrication. This work was funded by the National Institute of Standards and Technology (NIST), the Defense Advanced Research Projects Agency (DARPA) and the Strategic Environmental Research and Development Program (SERDP). This work is a partial contribution of NIST, an agency of the US government, and is not subject to copyright.

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Contributions

V.S. and P.D.D.S. carried out the experiments and noise analysis, S.K. fabricated the alkali vapour cell, and J.K. carried out the scaling analysis.

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Correspondence to John Kitching.

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Shah, V., Knappe, S., Schwindt, P. et al. Subpicotesla atomic magnetometry with a microfabricated vapour cell. Nature Photon 1, 649–652 (2007). https://doi.org/10.1038/nphoton.2007.201

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